Histocompatibility and distribution of ferroferric oxide nanoparticles / 中国组织工程研究

BACKGROUND:Ferroferric oxide (Fe3O4) nanoparticles are a research hotspot in drug delivery system, which can transport antineoplastic drugs to the lesion under external magnetic field. Additional y, its submicrons even can reach the tumor site several centimeters far away from the magnetic source. OBJECTIVE:To investigate the histocompatibility and in vivo distribution of Fe3O4 nanoparticles and to explore its application prospect and limitations as a drug carrier in the chemotherapy of osteosarcoma. METHODS:10.0 mg/kg Fe3O4 nanoparticles were administrated into Wistar rats via tail vein, then the rats were executed at 15, 60 and 120 minutes, respectively, and the rat lung, brain, heart, liver, kidney, hind limb and skeletal muscle were removed. The ferric ion content in each tissue was determined by atomic absorption spectrometer, and the morphological changes of different tissues were observed by hematoxylin-eosin staining at each time point. RESULTS AND CONCLUSION:After administrated for 15 minutes, the concentration of Fe3O4 nanoparticles in the liver and kidney reached peak, fol owed by a decrease at 60 and 120 minutes, but stil remained a high level. The concentration of Fe3O4 nanoparticles at three time points showed significant difference compared with the control group (P0.05), suggesting that the blood-brain barrier can inhibit the nanoparticle penetration. No overt morphological changes were found in each tissue after hematoxylin-eosin staining. In conclusion, the distribution of Fe3O4 nanoparticles conjugate sodium oleate in organism is influenced by the blood perfusion and mononuclear phagocyte system, and they cannot penetrate the blood-brain barrier and make no significant effect on tissues, but maintain a high level in the liver kidney and bone for a long-term, thus providing a theoretical basis for the drug delivery system in the magenetic hyperthermia therapy of malignant tumors.

The effect of repeated bonding of octyl-a-cyanoacrylate adhesive on human tibia cortical bone / 生物医学工程学杂志

During clinical operation, the repeated bonding of octyl-a-cyanoacrylate adhesive is necessary for satisfactory reduction and fixation. This is because the repeated bonding will change the morphologic characteristics of the bone surface in biomechanical study. The influence of repeated bonding of octyl-a-cyanoacrylate on fresh human tibia cortical bone was assessed in this experiment. First, we made the transverse fracture model on the anterior part of cortical bone of fresh human tibia shaft. After 24 hours of bonding, the tensile strength, shear strength and angular strength were tested; then we made the bonding for the second time and third time, tested the tensile strength, shear strength and angular strength respectively, and observed the change of tensile strength, shear strength and angular strength. We found the shear strength of the primary bonding being greater than that of the second bonding and the third bonding (P<0.05). The shear strength of the second bonding and the third bonding showed no statistically significant difference. The tensile strength, elastic modulus, rigidity coefficient and moment of area inertia exhibited no statistically difference between the first, second and third bonding. The repeated bonding of octyl-a-cyanoacrylate adhesive will change the morphologic characteristics of the bone surface, this will decrease the shear strength during the experiment. When the shear strength test is to be repeated, the residue of the adhesive on the surface of the bone bonded area should be removed. During clinical application, bonding should be performed only once in the area for resisting the shear strength.

Biomechanical study of medical hard tissue adhesive bonding butterfly fracture fragment in middle part of fresh human tibia / 生物医学工程学杂志

A medical hard tissue adhesive, octyl-a-cyanoacrylate, was tested in 6 fresh human tibiae. A 90 degrees butter-fly fracture fragment was made in the middle part of tibia by bandsaw. The compressive stress, torsional stress and angular deflection were assessed before and after osteoectomy respectively. After adhesive bonding, the compressive stress, torsional stress and angular deflection were tested again. The butterfly fracture fagment decreased the bending strength, torsion strength, yielding strength of tibia bone. In torsion test, the torque of tibia before osteoectomy is greater than bonded tibia, the bonded tibia is greater than that of the unbonded tibia. In compression test, before adhesive bonding broken, the compressive curve slope of tibia before osteoectomy is greater than that of bonded tibia, the bonded tibia is greater than that of the unbonded tibia. In angular deflection test before adhesive bonding of broken,the curve slope of tibia before osteoectomy is not different from that of bonded tibia (P>0.05), the slope the bonded tibia is greater than the slope of unbonded tibia(P<0.05). The elastic modulus, rigidity coefficient and moment of area inertia show no statistical difference between the bonded tibia and intact tibia. The used of medical hard tissue adhesive to bond the fracture fragment could improve the bending strength, torsion strength, yielding strength of tibia bone. In operation, it can reduce the soft tissue injury when the fracture fragment is being fixed, and this will benefit bone healing.